Holly Hills is an unincorporated community and a census-designated place located in and governed by Arapahoe County, Colorado, United States. Holly Hills is an enclave of the City and County of Denver. The CDP is a part of the Denver–Aurora–Lakewood, CO Metropolitan Statistical Area. The population of the Holly Hills CDP was 2,683 at the United States Census 2020. The Denver post office 80222 serves the area.